Infer return types

Motivation:

Removes unncessary explicit types that are inferred.

Modifications:

Infer types that are being returned from a function or computed variable.

Result:

Cleans up the code.

Sources/NIO/ChannelPipeline.swift

@@ -920,11 +920,11 @@ private extension CloseMode {
     var error: ChannelError {
         switch self {
         case .all:
-            return ChannelError.alreadyClosed
+            return .alreadyClosed
         case .output:
-            return ChannelError.outputClosed
+            return .outputClosed
         case .input:
-            return ChannelError.inputClosed
+            return .inputClosed
         }
     }
 }

Sources/NIO/PendingWritesManager.swift

@@ -333,7 +333,7 @@ final class PendingStreamWritesManager: PendingWritesManager {
                 return try triggerScalarFileWrite(scalarFileWriteOperation)
             case .nothingToBeWritten:
                 assertionFailure("called \(#function) with nothing available to be written")
-                return OneWriteOperationResult.writtenCompletely
+                return .writtenCompletely
             }
         }
     }